What a VLAN Is and Why It Helps

A switch connects many devices into one network. But sometimes you want those devices split into separate groups even though they share the same physical switch. A VLAN (Virtual Local Area Network) does exactly that: it logically divides one switch into several independent networks. This lesson explains what a VLAN is and the real benefits it brings to security, performance, and organization.

Without VLANs, every port on a switch belongs to the same broadcast domain. A broadcast domain is the set of devices that all receive a broadcast message. When one device broadcasts, every other device on the switch hears it. On a large flat network this means constant background chatter and no separation between different groups of users or devices.